NEW YORK (TheStreet) -- GT Advanced Technologies (GTAT) fell Wednesday after Credit Agricole downgraded the stock to "underperform" from "outperform" and set a $19 price target.

The stock has nearly tripled in value in the last year thanks largely to Apple's  (AAPL) interest in sapphire for the iPhone 6.

The stock was down 2.82% to $17.88 at 12:22 p.m.

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GTAT Chart GTAT data by YCharts

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